CN110865488B - Backlight module, display panel and display device - Google Patents

Abstract

Embodiments of the present application provide a backlight module, a display panel and a display device. The backlight module includes a metal backplane, a control unit and a switch; the metal backplane has a coupling voltage under the action of electric field coupling, the control unit is electrically connected to the metal backplane and the control terminal of the switch, and the first terminal of the switch is connected to the metal backplane. The backplane is electrically connected, and the second end of the switch is grounded; the control unit controls whether the switch is turned on according to the value of the coupling voltage, thereby controlling whether the metal backplane is grounded. The backlight module provided by this embodiment can control whether the metal backplane is grounded according to the value of the coupling voltage of the metal backplane, and realize the control of the potential of the metal backplane, thereby controlling the conductive film layer and the metal backplane in the display panel. The potential difference of the panel can control the potential difference between the two ends of the equivalent capacitor formed by the conductive film layer and the metal backplane to a small range, thereby effectively alleviating the screen whistling caused by the electrostriction of the film layer in the display panel. question called.

Description

Backlight module, display panel and display device

technical field

The present application relates to the field of display technology, and in particular, the present application relates to a backlight module, a display panel and a display device.

Background technique

The backlight module is one of the important structures of a liquid crystal display (LCD), and its function is to supply a light source with sufficient brightness and uniform distribution, so that the LCD can display images normally.

In order to ensure the reliability of the display panel, the current backlight module adopts a metal backplane, although the metal backplane can significantly improve the shock resistance and anti-drop performance of the display panel. However, the display panel has multiple conductive film layers. When a signal flows through a certain conductive film layer, the conductive film layer and the metal backplane form an equivalent capacitance, and this signal is equivalent to the equivalent capacitance applied to the above-mentioned equivalent capacitance. Voltage, if the voltage of the signal has a high frequency of change, for example, when the signal is a pulse-modulated signal, some of the film layers in the display panel will vibrate due to electrostriction, thereby causing the screen to whistle.

SUMMARY OF THE INVENTION

Aiming at the shortcomings of the prior art, the present application proposes a backlight module, a display panel and a display device, which are used to solve the problem that the conductive film layer and the metal back plate in the prior art form an equivalent capacitance, so that the display panel has an equivalent capacitance. The technical problem of screen whistling caused by electrostriction of some film layers.

In a first aspect, an embodiment of the present application provides a backlight module, the backlight module includes a metal backplane, a control unit and a switch; the metal backplane has a coupling voltage under the action of electric field coupling, and the control The unit is respectively electrically connected to the metal backplane and the control terminal of the switch, the first terminal of the switch is electrically connected to the metal backplane, and the second terminal of the switch is grounded; the control unit is based on the The value of the coupling voltage controls whether the switch is turned on, thereby controlling whether the metal backplane is grounded.

Optionally, the backlight module further includes: a transient diode, one end of the transient diode is electrically connected to the metal backplane, and the other end of the transient diode is grounded.

Optionally, the coupling voltage is a pulse modulation signal, and the peak value of the peak value of the pulse modulation signal is greater than the first specific potential; the switch includes a first transistor, and the first transistor is an N-type metal-oxide-semiconductor A transistor, the gate of the first transistor is the control terminal of the switch, the source of the first transistor is the first terminal of the switch, and the drain of the first transistor is the second terminal of the switch.

Optionally, the first specific potential is a ground potential, the control unit is a first voltage comparator, and the first voltage comparator includes a first input terminal, a second input terminal, a first voltage terminal, and a second voltage comparator. a voltage terminal and an output terminal; wherein the first input terminal and the second voltage terminal are both grounded, the second input terminal is electrically connected to the metal backplane, and the first voltage terminal is connected to the positive voltage input of the power supply The terminal is electrically connected, and the output terminal is electrically connected to the gate of the first transistor.

Optionally, the control unit is a first inverter, and the first inverter includes a second transistor, a third transistor, and an output terminal; the second transistor is a P-type metal-oxide-semiconductor transistor, The third transistor is an N-type metal-oxide-semiconductor transistor; the gate of the second transistor and the gate of the third transistor are both electrically connected to the metal backplane, and the source of the second transistor The terminal is electrically connected to the positive voltage input terminal of the power supply, the source terminal of the third transistor is grounded, the drain terminal of the second transistor and the drain terminal of the third transistor are both electrically connected to the output terminal, and the output terminal is electrically connected to the gate of the first transistor; the first specific potential is the turn-on voltage of the third transistor.

Optionally, the coupling voltage is a pulse modulation signal, and the peak value of the trough of the pulse modulation signal is less than the second specific potential; the switch includes a fourth transistor, and the fourth transistor is a P-type metal-oxide-semiconductor A transistor, the gate of the fourth transistor is the control terminal of the switch, the source of the fourth transistor is the first terminal of the switch, and the drain of the fourth transistor is the second terminal of the switch.

Optionally, the control unit is a second voltage comparator, and the second specific potential is a ground potential; the second voltage comparator includes a first input terminal, a second input terminal, a first voltage terminal, a second voltage comparator A voltage terminal and an output terminal, wherein the first input terminal is grounded, the second input terminal is electrically connected to the metal backplane, the first voltage terminal is grounded, and the second voltage terminal is powered by the negative voltage of the power supply The terminal is electrically connected, and the output terminal is electrically connected to the gate of the fourth transistor.

Optionally, the control unit is a second inverter; the second inverter includes a fifth transistor, a sixth transistor and an output terminal, and the fifth transistor is a P-type metal-oxide-semiconductor transistor, The sixth transistor is an N-type metal-oxide-semiconductor transistor; the gate of the fifth transistor and the gate of the sixth transistor are both electrically connected to the metal backplane, and the source of the fifth transistor The pole is grounded, the source of the sixth transistor is electrically connected to the negative voltage supply terminal of the power supply, the drain of the fifth transistor and the drain of the sixth transistor are both electrically connected to the output terminal; the output terminal is electrically connected to the gate of the fourth transistor; the second specific potential is the turn-on voltage of the fifth transistor.

In a second aspect, an embodiment of the present application provides a display panel, the display panel includes a conductive film layer and the above-mentioned backlight module.

Optionally, the conductive film layer includes a common electrode layer, and the common electrode layer is multiplexed into a touch electrode layer.

In a third aspect, an embodiment of the present application provides a display device, where the display device includes a power supply, a driving chip, and the above-mentioned display panel.

Optionally, the driving chip includes a display driving circuit and a touch driving circuit.

The beneficial technical effects brought by the technical solutions provided in the embodiments of the present application are:

The backlight module, display panel and display device provided by the embodiments of the present application can control whether the metal backplane is grounded according to the value of the coupling voltage of the metal backplane, and realize the control of the potential of the metal backplane, thereby controlling the display The potential difference between the conductive film layer and the metal backplane in the panel can control the potential difference between the two ends of the equivalent capacitor formed by the conductive film layer and the metal backplane to a small range, thereby effectively alleviating the film in the display panel due to electrical The problem of screen whistling caused by stretching.

Additional aspects and advantages of the present application will be set forth in part in the following description, which will become apparent from the following description, or may be learned by practice of the present application.

Description of drawings

The above and/or additional aspects and advantages of the present application will become apparent and readily understood from the following description of embodiments taken in conjunction with the accompanying drawings, wherein:

1 is a schematic structural diagram of a display panel in the related art;

2 is a schematic structural diagram of a backlight module provided by an embodiment of the present application;

3 is a schematic structural diagram of another backlight module provided by an embodiment of the present application;

4 is a schematic diagram of a specific structure of a backlight module provided by an embodiment of the present application;

5 is a timing control diagram of the backlight module shown in FIG. 4;

6 is a schematic diagram of a specific structure of another backlight module provided by an embodiment of the present application;

7 is a timing control diagram of the backlight module shown in FIG. 6;

8 is a schematic diagram of a specific structure of another backlight module provided by an embodiment of the present application;

9 is a timing control diagram of the backlight module shown in FIG. 8;

10 is a schematic diagram of a specific structure of still another backlight module provided by an embodiment of the application;

11 is a timing control diagram of the backlight module shown in FIG. 10;

FIG. 12 is a schematic structural diagram of a display panel according to an embodiment of the present application;

FIG. 13 is a schematic structural diagram of a display device according to an embodiment of the present application.

Reference number:

1-backlight module; 11-metal backplane; 12-control unit; 13-switch; 131-control end of switch; 132-first end of switch; 133-second end of switch;

12a-first voltage comparator; 12b-first inverter; 12c-second voltage comparator; 12d-second inverter;

M1-first transistor; M2-second transistor; M3-third transistor; M4-fourth transistor; M5-fifth transistor; M6-sixth transistor;

G1 - the gate of the first transistor; G2 - the gate of the second transistor; G3 - the gate of the third transistor; G4 - the gate of the fourth transistor; G5 - the gate of the fifth transistor; G6 - the sixth transistor the grid;

S1-source of the first transistor; S2-source of the second transistor; S3-source of the third transistor; S4-source of the fourth transistor; S5-source of the fifth transistor; S6-sixth transistor the source;

D1-drain of the first transistor; D2-drain of the second transistor; D3-drain of the third transistor; D4-drain of the fourth transistor; D5-drain of the fifth transistor; D6-sixth transistor the drain;

IN(+)-first input terminal; IN(-)-second input terminal; Out-output terminal; VDD-first voltage terminal; VEE-second voltage terminal;

VCC-power supply positive voltage input terminal; VSS-power supply negative voltage input terminal;

TVS-transient diode; m-conductive film layer; COM-common electrode layer.

Detailed ways

The application is described in detail below, and examples of embodiments of the application are illustrated in the accompanying drawings, wherein the same or similar reference numerals refer to the same or similar components or components having the same or similar functions throughout. Also, detailed descriptions of known technologies are omitted if they are not necessary for illustrating features of the present application. The embodiments described below with reference to the accompanying drawings are exemplary and are only used to explain the present application, but not to be construed as a limitation on the present application.

It will be understood by those skilled in the art that, unless otherwise defined, all terms (including technical and scientific terms) used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this application belongs. It should also be understood that terms, such as those defined in a general dictionary, should be understood to have meanings consistent with their meanings in the context of the prior art and, unless specifically defined as herein, should not be interpreted in idealistic or overly formal meaning to explain.

It will be understood by those skilled in the art that the singular forms "a", "an", "the" and "the" as used herein can include the plural forms as well, unless expressly stated otherwise. It should be further understood that the word "comprising" used in the specification of this application refers to the presence of stated features, integers, steps, operations, elements and/or components, but does not preclude the presence or addition of one or more other features, Integers, steps, operations, elements, components and/or groups thereof. It will be understood that when we refer to an element as being "connected" or "coupled" to another element, it can be directly connected or coupled to the other element or intervening elements may also be present. Furthermore, "connected" or "coupled" as used herein may include wirelessly connected or wirelessly coupled. As used herein, the term "and/or" includes all or any element and all combination of one or more of the associated listed items.

First of all, some terms involved in this application are introduced and explained:

(1) Electrostrictive effect: refers to the phenomenon of elastic deformation of the dielectric in the electric field. The magnitude of the electrostrictive effect is proportional to the field strength; usually, the changing electric field can make the dielectric vibrate due to the electrostrictive effect. The more severe the electric field changes, the more obvious the vibration of the dielectric due to electrostriction.

(2) Electric field coupling: Also known as electrostatic coupling or capacitive coupling, it is a coupling method due to the existence of distributed capacitance; for example, when one plate of the capacitor inputs a changing signal, the other plate of the capacitor is in the electric field. Signals with the same change under the action of coupling.

The inventors of the present application consider that, in order to improve the reliability of the display panel, the backlight module usually adopts a metal backplane (usually an iron backplane). As shown in FIG. 1 , the metal backplane 11 is usually grounded, that is, the potential of the metal backplane 11 is consistent with the ground potential (the ground potential in this application refers to the potential of the electrical ground). The display panel includes a plurality of conductive film layers, and the conductive film layers and the metal back plate 11 form an equivalent capacitance.

Normally, the conductive film layer that forms the equivalent capacitance with the metal backplane 11 is the common electrode layer COM. In the conventional display panel, the voltage of the common electrode layer COM is a constant voltage in the display stage. For some TDDI (Touch and Display Driver Integration, touch and display driver integration) LCD (Liquid Crystal Display, liquid crystal display) products, when the common electrode layer COM is multiplexed as touch electrodes, the common electrode layer COM usually inputs pulse modulation The signal is used as a touch scan signal.

There is a voltage difference between the common electrode layer COM and the ground potential, which is equivalent to applying the voltage difference across the equivalent capacitor formed by the common electrode layer COM and the grounded metal backplane 11 . When the display panel is in the display stage, the voltage on the common electrode layer COM is constant and has little difference with the ground potential (usually the difference is a few tenths of a volt), which will not cause the film layer in the display panel to vibrate due to electrostriction. , it will not cause the screen whistle problem. In the touch stage, the frequency of the pulse modulation signal is relatively large, and the peak or trough of the wave is very different from the ground potential, which can cause the film layer in the display panel to vibrate due to electrostriction, thereby causing the screen whistling problem. .

The backlight module, display panel and display device provided by the present application aim to solve the above technical problems in the prior art.

The technical solutions of the present application and how the technical solutions of the present application solve the above-mentioned technical problems will be described in detail below with specific examples.

This embodiment provides a backlight module. As shown in FIG. 2 , the backlight module includes a metal backplane 11 , a control unit 12 and a switch 13 ; the metal backplane 11 has a coupling voltage under the action of electric field coupling, and controls The unit 12 is electrically connected to the metal backplane 11 and the control terminal 131 of the switch 13 respectively, the first terminal 132 of the switch 13 is electrically connected to the metal backplane 1, and the second terminal 133 of the switch 13 is grounded; wherein, the control unit 12 is based on the coupling voltage. The value of , controls whether the switch 13 is turned on, thereby controlling whether the metal backplane 11 is grounded.

The backlight module provided in this embodiment can control whether the metal backplane 11 is grounded according to the value of the coupling voltage of the metal backplane 11 , and realize the control of the potential of the metal backplane 11 , thereby controlling the conductive film in the display panel. The potential difference between the layer and the metal backplane 11 can control the potential difference between the two ends of the equivalent capacitance formed by the conductive film layer and the metal backplane 11 to a small range, thereby effectively alleviating the film in the display panel due to electrostriction. And the problem of screen whistling.

Optionally, as shown in FIG. 3, in the backlight module provided in this embodiment, the backlight module further includes a transient diode TVS, one end of the transient diode TVS is electrically connected to the metal backplane 11, and the transient diode TVS is electrically connected to the metal backplane 11. The other end is grounded.

The metal backplane 11 may generate static electricity during operation. If static electricity is generated when the switch 13 is turned off and the metal backplane 11 is not grounded, the components in the backlight module may be damaged by static electricity, and even the backlight module may be removed from the display panel. Devices in other structures outside the group are also damaged by electrostatics.

In this embodiment, by setting the transient diode TVS, the static electricity on the metal backplane 11 can be released through the transient diode TVS, thereby protecting the safety of the backlight module and other components in the display panel except the backlight module.

For a display panel in which the peak value of the peak value of the pulse modulation signal in the touch phase is greater than the first specific potential, the metal backplane 11 should be disconnected from the ground at least when the pulse modulation signal is at the peak value, so that the metal backplane 11 maintains and pulses The peaks of the modulated signal have the same coupling voltage, thereby reducing the voltage difference between the conductive film layer and the metal backplane 11 , thereby alleviating the screen whistling caused by the electrostrictive effect of the film layer in the display panel. For the display panel using such a pulse modulation signal, the present application provides the following specific embodiments, which will be described in detail below with reference to FIG. 4 to FIG. 7 .

As shown in FIG. 4 or FIG. 6 , optionally, the switch 13 includes a first transistor M1 , and the first transistor M1 is an N-type metal-oxide-semiconductor transistor, that is, an NMOS transistor. The gate of the NMOS transistor is turned on when the gate input is high, and turned off when the gate input is low. The gate G1 of the first transistor M1 is the control terminal 131 of the switch 13 , the source S1 of the first transistor M1 is the first terminal 132 of the switch 13 , and the drain D1 of the first transistor M1 is the second terminal of the switch 13 133.

In a specific embodiment, as shown in FIG. 4 , this embodiment provides a backlight module, in which the control unit 12 is a first voltage comparator 12a.

Specifically, the first voltage comparator 12a includes a first input terminal IN(+), a second input terminal IN(-), a first voltage terminal VDD, a second voltage terminal VEE and an output terminal Out, wherein the first input terminal IN(+) is grounded, the second input terminal IN(-) is electrically connected to the metal backplane 11, the first voltage terminal VDD is electrically connected to the positive voltage supply terminal VCC, the second voltage terminal VEE is grounded, and the output terminal Out is connected to the first The gate G1 of the transistor M1 is electrically connected. The voltage between the first voltage terminal VDD and the second voltage terminal VEE is used to ensure the normal operation of the voltage comparator 12a, that is, a positive voltage is used for power supply.

Please refer to Figure 4 and Figure 5. The first specific potential is the ground potential (ground potential). There are two situations in which the peak value of the peak of the pulse modulation signal is greater than the ground potential. The first situation is that the peak value of the trough of the pulse modulation signal is also greater than the ground potential. potential, while the second case is where the peaks of the troughs of the pulsed signal are below ground potential.

For the first case, since the peak value of the trough of the pulse modulation signal is also greater than the ground potential, the coupling voltage of the metal backplane 11 is higher than the ground potential when it is in the trough. Even if the coupling voltage of the metal backplane 11 is in the trough, the first The potential (GND) of the first input terminal IN(+) of a voltage comparator 12a is lower than the potential of the second input terminal IN(-), and the output terminal Out outputs a low level. Therefore, when the metal backplane 11 is coupled with the pulse modulation signal, the output terminal Out outputs a continuous low level, so that the first transistor M1 is continuously turned off, that is, the metal backplane 11 is coupled with the pulse modulation signal. The plate 11 is disconnected from the ground, so that the coupling voltage of the metal back plate 11 is also basically consistent with the pulse modulation signal, which can make the voltage difference between the metal back plate 11 and the conductive film layer basically zero, and more importantly, can ensure the conductive film. The voltage difference between the layers and the equivalent capacitance formed by the metal backplane 11 is kept constant, so as to avoid the electrostrictive effect of the film layer in the display panel.

For the second situation, when the coupling voltage of the metal backplane 11 is at the peak, the voltage input by the second input terminal IN(-) of the first voltage comparator 12a is higher than the ground potential. The potential (ground potential) of one input terminal IN(+) is lower than the potential of the second input terminal IN(-), then the output terminal Out outputs a low level, and the first transistor M1 is turned off, that is, the metal backplane 11 is disconnected from the ground. open so that the coupling voltage of the metal backplane 11 maintains the current peak voltage of the pulse modulation signal, and the voltage difference between the metal backplane 11 and the conductive film layer is substantially zero at this time. When the coupling voltage of the metal backplane 11 is in a valley, the voltage input to the second input terminal IN(-) of the first voltage comparator 12a is lower than the ground potential. At this time, the first input terminal IN(+) of the voltage comparator 12a ) potential (ground potential) is higher than the potential of the second input terminal IN(-), then the output terminal Out outputs a high level, the first transistor M1 is turned on, that is, the metal backplane 11 is connected to the ground so that the metal backplane 11 The voltage is the ground potential. Since the voltage of the trough of the pulse modulation signal is not much different from the ground potential, the voltage difference between the metal backplane 11 and the conductive film layer is also small. Therefore, although the voltage difference between the two ends of the equivalent capacitor formed by the conductive film layer and the metal back plate 11 changes periodically, the electrostrictive effect can also be effectively reduced due to the small amplitude of the change.

It should be noted that the pulse modulation signal in the first case and the pulse modulation signal in the second case in the graph in FIG. 5 are only drawn in the same diagram for the convenience of comparison. In fact, the pulse modulation signal in the first case is The modulation signal and the pulse modulation signal in the second case do not exist in the same display panel at the same time, but different display panels can select the pulse modulation signal in the first case or the second case as the scan signal in the touch stage. In FIG. 7 , FIG. 9 and FIG. 11 , the pulse modulation signal of the first case and the pulse modulation signal of the second case are only drawn in the same figure for the convenience of comparison, and will not be described in detail later.

In the display stage, the coupling voltage of the metal backplane 11 is the common voltage of the common electrode layer (which can be set to be slightly lower than the low level), that is, the voltage input by the second input terminal IN(-) of the voltage comparator 12a is lower than ground potential, at this time, the potential (GND) of the first input terminal IN(+) of the voltage comparator 12a is higher than the potential of the second input terminal IN(-), then the first output terminal Out1 outputs a high level, the first The transistor M1 is turned on, and the metal backplane 11 is grounded.

In this embodiment, the first voltage comparator 12a is used as the control unit 12, when the peak value of the pulse modulation signal in the conductive film layer is greater than the ground potential, it can effectively reduce or even prevent the film layer in the display panel from generating electrocution It can improve or even completely avoid the screen whistling problem caused by electrostriction.

In another specific embodiment, as shown in FIG. 6 , this embodiment provides a backlight module, in which the control unit 12 is a first inverter 12b.

Specifically, the first inverter 12b includes a second transistor M2, a third transistor M3 and a second output terminal Out2, the second transistor M2 is a P-type metal-oxide-semiconductor transistor, that is, a PMOS transistor, and the third transistor M3 is N-type metal-oxide-semiconductor transistor, namely NMOS transistor; the gate G2 of the second transistor M2 and the gate G3 of the third transistor M3 are both electrically connected to the metal backplane 11, and the source S2 of the second transistor M2 is connected to the power supply The voltage terminal VCC is electrically connected, the source S3 of the third transistor M3 is grounded, the drain D2 of the second transistor M2 and the drain D3 of the third transistor M3 are both electrically connected to the second output terminal Out2; the second output terminal Out2 is electrically connected to the second output terminal Out2. The gate G1 of a transistor M1 is electrically connected.

Please refer to FIG. 6 and FIG. 7 , the first specific potential is the turn-on voltage V1 of the third transistor M3, ie V1-V _S3 =V1-V _GND =V _th3 , it can be known that V1=V _th3 +V _GND . It can be seen that the pulse modulation signal can be adapted by designing the threshold voltage V _th3 of the third transistor M3.

There are two situations in which the peak value of the peak of the pulse modulation signal is greater than the turn-on voltage V1. The first case is that the peak value of the trough of the pulse modulation signal is also greater than the turn-on voltage V1, and the second case is that the peak value of the trough of the pulse modulation signal is lower than the turn-on voltage V1. voltage V1.

For the first case, since the peak value of the trough of the pulse modulation signal is also greater than the turn-on voltage V1, the coupling voltage of the metal backplane 11 is higher than the turn-on voltage V1 when it is in the trough, even if the coupling voltage of the metal backplane 11 is in the trough. , the third transistor M3 can also be turned on, and the second output terminal Out outputs a continuous low level (ground potential), so that the first transistor M1 is continuously turned off, that is, the metal backplane 11 is coupled with the pulse modulation signal. The backplane 11 is disconnected from the ground, so that the coupling voltage of the metal backplane 11 is also basically the same as the pulse modulation signal, which can make the voltage difference between the metal backplane 11 and the conductive film layer basically zero, and more importantly, can ensure electrical conductivity. The voltage difference between the film layer and the equivalent capacitance formed by the metal back plate 11 is kept constant, so as to avoid the electrostrictive effect of the film layer in the display panel.

For the second case, the turn-on voltage of the second transistor M2 can be set so that the second transistor M2 can be turned on when the coupling voltage of the metal backplane 11 is in a valley. Then when the coupling voltage of the metal backplane 11 is at the peak, the third transistor M3 is turned on, and the second output terminal Out2 outputs the ground potential (low level), so that the first transistor M1 is turned off so that the metal backplane 11 is connected to the ground. disconnected, so that the metal backplane 11 maintains the current high level. When the coupling voltage of the metal backplane 11 is in the valley, the second transistor M2 is turned on, the second output terminal Out2 outputs the power supply voltage (VCC), and the first transistor M1 is turned on, so that the first transistor M1 is turned on, so that the metal backplane is turned on. 11 is connected to the ground, that is, the voltage of the metal backplane 11 is the ground potential. Since the voltage of the trough of the pulse modulation signal is not much different from the ground potential, the voltage difference between the metal backplane 11 and the conductive film layer is also small. Therefore, although the voltage difference between the two ends of the equivalent capacitor formed by the conductive film layer and the metal back plate 11 changes periodically, the electrostrictive effect can also be effectively reduced due to the small amplitude of the change.

In the display stage, the coupling voltage of the metal backplane 11 is the common voltage of the common electrode layer (usually slightly lower than the low level), and the third transistor M3 can be turned off by designing the threshold voltages of the second transistor M2 and the third transistor M3, When the second transistor M2 is turned on, the second output terminal Out2 outputs a high level, the first transistor M1 is turned on, and the metal backplane 11 is grounded.

In this embodiment, the first inverter 12b is used as the control unit 12. When the peak value of the pulse modulation signal in the conductive film layer is greater than the turn-on level V1 of the third transistor M3, it can effectively reduce or even avoid the display panel. The electrostrictive effect of the film layer occurs, thereby improving or even completely avoiding the problem of screen whistling caused by electrostriction.

For a display panel in which the peak value of the trough of the pulse modulation signal in the touch phase is smaller than the second specific potential, the metal backplane 11 should be disconnected from the ground at least when the pulse modulation signal is in the trough, so that the metal backplane 11 maintains the pulse The coupling voltage of the modulated signal is the same as the valley, thereby reducing the voltage difference between the conductive film layer and the metal backplane 11, thereby alleviating the screen whistling caused by the electrostrictive effect of the film layer in the display panel. For the display panel using such a pulse modulation signal, the present application provides the following specific embodiments, which will be described in detail below with reference to FIG. 8 to FIG. 11 .

As shown in FIG. 8 or FIG. 10 , optionally, the switch 13 includes a fourth transistor M4 , and the fourth transistor M4 is a P-type metal-oxide-semiconductor transistor, that is, a PMOS transistor. The gate of the PMOS transistor is turned off when the gate input is high, and is turned on when the gate input is low. The gate G4 of the fourth transistor M4 is the control terminal 131 of the switch 13 , the source S4 of the fourth transistor M4 is the first terminal 132 of the switch 13 , and the drain D4 of the fourth transistor M4 is the second terminal of the switch 13 133.

In a specific embodiment, as shown in FIG. 8 , this embodiment provides a backlight module, in which the control unit 12 is a second voltage comparator 12c.

Specifically, the second voltage comparator 12c includes a first input terminal IN(+), a second input terminal IN(-), a first voltage terminal VDD, a second voltage terminal VEE and an output terminal Out, wherein the first input terminal IN(+) is grounded, the second input terminal IN(-) is electrically connected to the metal backplane 11, the first voltage terminal VDD is grounded, the second voltage terminal VEE is electrically connected to the negative voltage supply terminal VSS, and the output terminal Out is electrically connected to the fourth The gate G4 of the transistor M4 is electrically connected. The voltage between the first voltage terminal VDD and the second voltage terminal VEE is used to ensure the normal operation of the voltage comparator 12a, that is, a negative voltage is used to supply power.

Please refer to Figure 8 and Figure 9. The second specific potential is the ground potential. There are two situations in which the peak value of the trough of the pulse modulation signal is lower than the ground potential. The first situation is that the peak value of the peak of the pulse modulation signal is also lower than the ground potential. In the second case, the peak value of the peak of the pulse modulated signal is higher than the ground potential.

For the first case, since the peak value of the peak of the pulse modulation signal is also lower than the ground potential, the coupling voltage of the metal backplane 11 is also lower than the ground potential when it is at the peak, even if the coupling voltage of the metal backplane 11 is at the peak, The potential (ground potential) of the first input terminal IN(+) of the second voltage comparator 12c is higher than the potential of the second input terminal IN(-), and the output terminal Out outputs a high level. Therefore, when the metal backplane 11 is coupled with the pulse modulation signal, the output terminal Out outputs a continuous high level, so that the fourth transistor M4 is continuously turned off, that is, the metal backplane 11 is coupled with the pulse modulation signal. The plate 11 is disconnected from the ground, so that the coupling voltage of the metal back plate 11 is also basically consistent with the pulse modulation signal, which can not only make the voltage difference between the metal back plate 11 and the conductive film layer basically zero, but also ensure that the conductive film layer and the The voltage difference between the equivalent capacitors formed by the metal back plate 11 is kept constant, so as to avoid the electrostrictive effect of the film layer in the display panel.

For the second case, when the coupling voltage of the metal backplane 11 is in the valley, the voltage input by the second input terminal IN(-) of the second voltage comparator 12c is lower than the ground potential. At this time, the second voltage comparator 12c The potential (ground potential) of the first input terminal IN(+) is higher than the potential of the second input terminal IN(-), the output terminal Out outputs a high level, and the fourth transistor M4 is turned off, that is, the metal backplane 11 and the The ground is disconnected so that the coupling voltage of the metal backplane 11 maintains the voltage of the current valley of the pulse modulation signal, and the voltage difference between the metal backplane 11 and the conductive film layer is substantially zero at this time. When the coupling voltage of the metal backplane 11 is at a peak, the voltage input to the second input terminal IN(-) of the second voltage comparator 12c is higher than the ground potential, and at this time, the first input terminal IN(-) of the second voltage comparator 12c (+) potential (ground potential) is lower than the potential of the second input terminal IN (-), then the output terminal Out outputs a low level, and the fourth transistor M4 is turned on, that is, the metal backplane 11 is connected to the ground so that the metal backplane is connected to the ground. The voltage of the plate 11 is the ground potential. Since the voltage of the peak of the pulse modulation signal is not much different from the ground potential, the voltage difference between the metal back plate 11 and the conductive film layer is also small. Therefore, although the voltage difference between the two ends of the equivalent capacitor formed by the conductive film layer and the metal back plate 11 changes periodically, the electrostrictive effect can also be effectively reduced due to the small amplitude of the change.

In the display stage, the coupling voltage of the metal back plate 11 is the common voltage of the common electrode layer (which can be set to be slightly higher than the ground potential), that is, the voltage input by the second input terminal IN(-) of the second voltage comparator 12c is high At the ground potential, at this time, the potential (ground potential) of the first input terminal IN(+) of the second voltage comparator 12c is lower than the potential of the second input terminal IN(-), and the output terminal Out outputs a low level, The fourth transistor M4 is turned on, and the metal backplane 11 is grounded.

In this embodiment, using the second voltage comparator 12c as the control unit 12, when the peak value of the trough of the pulse modulation signal in the conductive film layer is lower than the ground potential, it can effectively reduce or even prevent the film layer in the display panel from generating electricity. It can improve or even completely avoid the screen whistling problem caused by electrostriction.

In another specific embodiment, as shown in FIG. 10 , this embodiment provides a backlight module, in which the control unit 12 is a second inverter 12d.

Specifically, the second inverter 12d includes a fifth transistor M5, a sixth transistor M6 and an output terminal Out, the fifth transistor M5 is a P-type metal-oxide-semiconductor transistor, that is, a PMOS transistor, and the sixth transistor M6 is an N-type transistor A metal-oxide-semiconductor transistor, namely an NMOS transistor; the gate G5 of the fifth transistor M5 and the gate G6 of the sixth transistor M6 are both electrically connected to the metal backplane 11, the source S5 of the fifth transistor M5 is grounded, and the sixth transistor M6 is electrically connected to the metal backplane 11. The source S6 of the transistor M6 is electrically connected to the negative voltage supply terminal VSS of the power supply, the drain D5 of the fifth transistor M5 and the drain D6 of the sixth transistor M6 are both electrically connected to the output terminal Out; the output terminal Out is electrically connected to the fourth transistor M4. The gate G4 is electrically connected.

10 and FIG. 11, the second specific potential is the turn-on voltage V2 of the fifth transistor M5, ie V2-V _S5 =V2-V _GND =V _th5 , it can be known that V2=V _th5 +V _GND . It can be seen that the pulse modulation signal can be adapted by designing the threshold voltage V _th5 of the fifth transistor M5.

The peak value of the trough of the pulse modulation signal is less than the turn-on voltage V2. There are two cases. The first case is that the peak value of the peak of the pulse modulation signal is also smaller than the turn-on voltage V2, and the second case is that the peak value of the pulse modulation signal is higher than the turn-on voltage V2. voltage V2.

For the first case, since the peak value of the peak of the pulse modulation signal is also smaller than the turn-on voltage V2, the coupling voltage of the metal backplane 11 is lower than the turn-on voltage V2 when it is at the peak, even if the coupling voltage of the metal backplane 11 is at the peak. , the fifth transistor M5 can also be turned on, and the output terminal Out outputs a continuous ground potential, so that the fourth transistor M4 is continuously turned off, that is, the metal backplane 11 is disconnected from the ground in the process of coupling the metal backplane 11 to the pulse modulation signal. , so that the coupling voltage of the metal backplane 11 is also basically consistent with the pulse modulation signal, which can not only make the voltage difference between the metal backplane 11 and the conductive film layer basically zero, but also ensure that the conductive film layer and the metal backplane 11 constituted The voltage difference between the equivalent capacitors is kept constant, thereby avoiding the electrostrictive effect of the film layers in the display panel.

For the second case, the turn-on voltage of the sixth transistor M6 can be set so that the sixth transistor M6 can be turned on when the coupling voltage of the metal backplane 11 is at a peak. Then when the coupling voltage of the metal backplane 11 is in the valley, the fifth transistor M5 is turned on, and the output terminal Out outputs the ground potential, so that the fourth transistor M4 is turned off to disconnect the metal backplane 11 from the ground, thereby making the metal backplane 11 disconnected from the ground. Plate 11 maintains the current potential. When the coupling voltage of the metal backplane 11 is at the peak, the sixth transistor M6 is turned on, the output terminal Out outputs the power supply negative voltage VSS, and the fourth transistor M4 is turned on to connect the metal backplane 11 to the ground, that is, the metal backplane The voltage of 11 is the ground potential. Since the voltage of the peak of the pulse modulation signal is not much different from the ground potential, the voltage difference between the metal backplane 11 and the conductive film layer is also small. Therefore, although the voltage difference between the two ends of the equivalent capacitor formed by the conductive film layer and the metal back plate 11 changes periodically, the electrostrictive effect can also be effectively reduced due to the small amplitude of the change.

In the display stage, the coupling voltage of the metal backplane 11 is the common voltage of the common electrode layer (which can be set to be slightly higher than the ground potential), and the fifth transistor M5 can be turned off by designing the threshold voltages of the fifth transistor M5 and the sixth transistor M6 , and the sixth transistor M6 is turned on, the output terminal Out outputs the negative power supply voltage VSS, so that the fourth transistor M4 is turned on, and the metal backplane 11 is grounded.

In this embodiment, the second inverter 12d is used as the control unit 12. When the peak value of the trough of the pulse modulation signal in the conductive film layer is lower than the turn-on level V2 of the fifth transistor M5, the display panel can be effectively reduced or even avoided. The electrostrictive effect occurs in the film layer in the device, thereby improving or even completely avoiding the problem of screen whistling caused by electrostriction.

Based on the same inventive concept, this embodiment provides a display panel. As shown in FIG. 12 , the display panel includes a conductive film layer m and the backlight module 1 in the above-mentioned embodiment. The beneficial effects will not be repeated here.

Optionally, the conductive film layer m includes a common electrode layer COM that is multiplexed into a touch electrode layer except for the common electrode layer COM.

Specifically, the conductive film layer further includes a gate layer, a source-drain electrode layer, a pixel electrode layer, and the like.

Specifically, the display panel further includes an insulating layer between the conductive film layers, and both the conductive film layer and the insulating layer may vibrate due to electrostriction.

When the display panel is in the display stage, the potential of the common electrode layer is a constant potential that is not much different from the ground potential, and the metal backplane 11 is connected to the ground. Therefore, the voltage difference between the metal backplane 11 and the common electrode layer COM is small and The pressure difference remains unchanged, and the screen whistling problem will not be caused by electrostriction.

When the display panel is in the touch stage, the common electrode layer is multiplexed into a touch electrode layer, the touch scan signal of the common electrode layer is a pulse modulation signal, the coupling voltage of the metal backplane 11 is approximately the same as the pulse modulation signal, and the metal backplane 11 is disconnected from ground at least when the pulse modulation signal is a peak (the peak of the pulse modulation signal is greater than the first specific potential) or the trough (the peak of the pulse modulation signal is less than the second specific potential), so that the common electrode layer COM and the metal backplane 11 The pressure difference of the display panel is constant, or the amplitude of the change of the pressure difference is small, which will not cause the screen whistling problem caused by the electrostriction of the film layer in the display panel.

Based on the same inventive concept, this embodiment provides a display device. As shown in FIG. 13 , the display device includes a power supply, a driving chip, and the display panel in the above-mentioned embodiment, and has the beneficial effects of the display panel in the above-mentioned embodiment. It is not repeated here.

Specifically, the power supply in this embodiment may be electrically connected to the positive voltage input terminal VCC of the power supply in the above embodiments, or electrically connected to the negative voltage input terminal VSS in the above embodiments.

Specifically, the driving chip in this embodiment includes a display driving circuit and a touch driving circuit, that is, the display panel is a TDDI LCD display device.

By applying the embodiments of the present application, at least the following beneficial effects can be achieved:

The backlight module, display panel and display device provided by the embodiments of the present application can control whether the metal backplane is grounded according to the value of the coupling voltage of the metal backplane, and realize the control of the potential of the metal backplane, thereby controlling the display The potential difference between the conductive film layer and the metal backplane in the panel can control the potential difference between the two ends of the equivalent capacitor formed by the conductive film layer and the metal backplane to a small range, thereby effectively alleviating the film in the display panel due to electrical The problem of screen whistling caused by stretching.

The above are only part of the embodiments of the present application. It should be pointed out that for those skilled in the art, without departing from the principles of the present application, several improvements and modifications can also be made. It should be regarded as the protection scope of this application.

Claims (12)

1. A backlight module, characterized in that, comprising a metal backplane, a control unit and a transistor as a switch; The metal backplane has a coupling voltage under the action of electric field coupling, the control unit is electrically connected to the metal backplane and the gate of the transistor, and the source of the transistor is electrically connected to the metal backplane. connected, the drain of the transistor is grounded; The control unit controls whether the transistor is turned on according to the value of the coupling voltage, thereby controlling whether the metal backplane is grounded to control the potential of the metal backplane, thereby reducing the difference between the metal backplane and the display panel. The potential difference of the conductive film layer; The control unit is a voltage comparator. 2. The backlight module according to claim 1, further comprising: A transient diode, one end of the transient diode is electrically connected to the metal backplane, and the other end of the transient diode is grounded. 3. The backlight module according to claim 1 or 2, wherein the coupling voltage is a pulse modulation signal, and the peak value of the peak of the pulse modulation signal is greater than the first specific potential; The transistor used as a switch is a first transistor, and the first transistor is an N-type metal-oxide-semiconductor transistor; the first specific potential is a ground potential, the control unit is a first voltage comparator, and the The first voltage comparator includes a first input terminal, a second input terminal, a first voltage terminal, a second voltage terminal and an output terminal; The first input terminal and the second voltage terminal are both grounded, the second input terminal is electrically connected to the metal backplane, the first voltage terminal is electrically connected to the positive voltage input terminal of the power supply, and the The output terminal is electrically connected to the gate of the first transistor. 4. The backlight module according to claim 1 or 2, wherein the coupling voltage is a pulse modulation signal, and the peak value of the trough of the pulse modulation signal is smaller than the second specific potential; The transistor used as a switch is a fourth transistor, and the fourth transistor is a P-type metal-oxide-semiconductor transistor; the control unit is a second voltage comparator, and the second specific potential is a ground potential; The second voltage comparator includes a first input terminal, a second input terminal, a first voltage terminal, a second voltage terminal and an output terminal, wherein the first input terminal is grounded, and the second input terminal is connected to the The metal backplane is electrically connected, the first voltage terminal is grounded, the second voltage terminal is electrically connected to the negative voltage supply terminal of the power supply, and the output terminal is electrically connected to the gate of the fourth transistor. 5. A backlight module, comprising a metal backplane, a control unit and a transistor as a switch; The metal backplane has a coupling voltage under the action of electric field coupling, the control unit is electrically connected to the metal backplane and the gate of the transistor, and the source of the transistor is electrically connected to the metal backplane. connected, the drain of the transistor is grounded; The control unit controls whether the transistor is turned on according to the value of the coupling voltage, thereby controlling whether the metal backplane is grounded to control the potential of the metal backplane, thereby reducing the difference between the metal backplane and the display panel. The potential difference of the conductive film layer; The control unit is an inverter. 6. The backlight module according to claim 5, further comprising: A transient diode, one end of the transient diode is electrically connected to the metal backplane, and the other end of the transient diode is grounded. 7. The backlight module according to claim 5 or 6, wherein the coupling voltage is a pulse modulation signal, and the peak value of the peak of the pulse modulation signal is greater than the first specific potential; The transistor used as a switch is a first transistor, and the first transistor is an N-type metal-oxide-semiconductor transistor; The control unit is a first inverter, and the first inverter includes a second transistor, a third transistor and an output terminal; The second transistor is a P-type metal-oxide-semiconductor transistor, and the third transistor is an N-type metal-oxide-semiconductor transistor; The gate of the second transistor and the gate of the third transistor are both electrically connected to the metal backplane, the source of the second transistor is electrically connected to the positive voltage input end of the power supply, and the third transistor is The source is grounded, the drain of the second transistor and the drain of the third transistor are both electrically connected to the output terminal, and the output terminal is electrically connected to the gate of the first transistor; The first specific potential is the turn-on voltage of the third transistor. 8. The backlight module according to claim 5 or 6, wherein the coupling voltage is a pulse modulation signal, and the peak value of the trough of the pulse modulation signal is less than a second specific potential; The transistor used as a switch is a fourth transistor, and the fourth transistor is a P-type metal-oxide-semiconductor transistor; the control unit is a second inverter; The second inverter includes a fifth transistor, a sixth transistor and an output terminal, the fifth transistor is a P-type metal-oxide-semiconductor transistor, and the sixth transistor is an N-type metal-oxide-semiconductor transistor ; The gate of the fifth transistor and the gate of the sixth transistor are both electrically connected to the metal backplane, the source of the fifth transistor is grounded, and the source of the sixth transistor is negatively connected to the power supply The power supply terminal is electrically connected, the drain of the fifth transistor and the drain of the sixth transistor are both electrically connected to the output terminal; the output terminal is electrically connected to the gate of the fourth transistor; The second specific potential is the turn-on voltage of the fifth transistor. 9. A display panel, characterized in that, comprising: conductive film layer; The backlight module according to any one of claims 1-4, or the backlight module according to any one of claims 5-8. 10 . The display panel according to claim 9 , wherein the conductive film layer comprises a common electrode layer, and the common electrode layer is multiplexed into a touch electrode layer. 11 . 11 . A display device comprising a power supply and a driving chip, further comprising the display panel according to claim 9 or 10 . 12 . The display device according to claim 11 , wherein the driving chip comprises a display driving circuit and a touch driving circuit. 13 .

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